Ferrous alloy



Patented Oct. 10, 1939 PATENT OFFICE FERROUS ALLOY George Charlton,Detroit, Mich, assignor to Eaton Manufacturing Company,

Cleveland,

Ohio, a corporation of Ohio No Drawing. Continuation of applicationSerial No. 269,164, April 21, 1939. This application July 15, 1939,Serial No. 284,749

3 Claims.

This invention relates to steel alloys especially adapted for use asvalve seat rings and in lining cylinder sleeves for internal combustionengines and similar uses where it is necessary to have a material thatis highly resistant to wear and corrosion, both at normal temperaturesand at relatively high temperatures such as 1200 F. This application isa-continuation of applicants copending application for Ferrous alloy,Serial 0 Number 269,164, filed April 21, 1939.

The term wear resisting as applied to ferrous alloys may have differentmeanings. For instance, one piece of metal may work Well in contact witha piece of another metal and the one will show no wear and the otherconsiderable wear. On the other hand, two pieces of different metals canwork in contact under the same conditions as in the first instance, andneither will show appreciable wear although the difference in hardnessbetween the metals may be as great in one instance as in the other. Thetendency of a metal to pick up particles from another metal with whichit is in working contact is aggravated as the temperature is increased.

Alloys which have good wear resistance at room temperature may Wearrapidly when the operating temperature increases to the neighborhood of1200 F. The same is true as to corrosion resistance and an alloy whichmay exhibit satisfactory corrosion resistance at room temperature maycorrode rapidly at an elevated temperature of approximately 1200 F.

In order to improve liners for the cylinders of internal combustionengines used in automobiles and aircraft and the like, it has beennecessary to produce an alloy which will have improved properties withrespect to wear resistance and corrosion in that part of the cylinderwhich is subjected to maximum heat. The wear resistance, which is anobject of this invention, is the ability of the alloy to resist pick upeither under hot or cold conditions, and also show a In addition to thequalities above stated as necessary for an alloy for making cylinderliners or valve seats, it is important that the alloy, when it has tolend itself to the making of histeel tube with the alloy by the spinningprocess in which the molten metal is deposited on the inside of the tubeby the rotation of the latter at high speeds. Valve seat rings have alsobeen made from this alloy and manufactured by the spinning method, andactual performance tests have determined them to be a good commercialjob. A further desirable property of the alloy in the case of seat ringsis a hardness in the as cast or as spun condition which permits thefinal finishing of the parts by machining, that is to say, the alloy hasmachinability and yet is sufficiently high in hot hardness to provide agood wearing surface at elevated tem peratures up to 1200 F. forsustained periods of time. The fact that the stock is machinableprovides, in certain instances, the very desirable feature of being ableto ream the face of the seat after assembly or use in the motor block.

Accordingly, the primary object of this invention is to provide aferrous alloy having the above and other desirable properties which willbe apparent to those skilled in this art and especially adaptable foruse in internal combustion engine parts subjected to relatively highoperating temperatures, and highly corrosive conditions, yet having adegree of hardness providing machinability and a sufliciently lowmelting point permitting manufacture or processing by centrifugalcasting in ordinary steel tubing.

An alloy which has the requirements above stated, which is within thecontemplation of this invention, and produces an improved engine partmay be comprised of a range of material substantially as follows:

It is, of course, recognized that the elements sulphur and phosphorusare'present in all ordinary ferrous alloys and ordinarily an effort ismade to keep these elements as'low in percentage as possible, becausetheir presence creates problems of forgeability and segregation. Theelement manganese may be present in the alloy because of its presence inthe base materials used to make the alloy following the ordinarypractice of alloy making, and its presence does not adversely affect theproperties of the alloy.

In the case of the sulphur and phosphorus content in this application,low or high percentages can be used and a certain structural conditionwhich they provide can be utilized to obtain increased degrees ofwear-resistance. When this material is employedto produce a cylinderliner or seat by the spinning process, problems of forgeability are notencountered; and, also; because of the centrifugal action, constituentsformed by the elements are uniformly distributed and segregated areas donot form.

It is preferable, 'inthe case of the sulphur and phosphorus content, tohave, when one of the elements is high, a low content of the other; andthe intentional use of an upper content of these elements well beyondthe conventional range thereof is believed novel in the controlledpercentages stated. The high sulphur or phosphorus content produces inthe material a structural network which has the surface property ofpresenting a wear-resisting face which substantially reduces galling ormetal pick up when subjected to a metal-to-metal sliding.

Tests under heat and corrosive conditions with more severe conditionsthan encountered in an engine have proven the above material to wearwell, retain its hardness and due to the high nickel-chromium content tobe an excellent cor-. rosion resistor.

One specific analysis of this alloy which fills theabove requirements isapproin'mately as fol- In this heat" of the alloy it will be noted thatthe phosphorus content is relatively low and the sulphur contentrelatively high, in accordance with the teaching of this invention.

Another specific ferrous alloy of slightly different composition, alsoin accordance with the teaching of this invention, has an analysis sustantially as follows:

Per cent Carbon .91 Chromium- 11.40 Silicon v 1.37 Nickel 33.34 Boron1.78 Phosphorus 1.09 Sulphur .02 Iron Balance It will be noted that thisspecific alloy as aforementioned has in this instance a high phosphoruscontent and a low sulphur content in accordance with the teaching ofthis invention. However.

the use of the aforementioned relationship between the phosphorus andsulphur content is not the controlling factor in securing the desiredproperties of this alloy, because in certain instances it may bedesirable to hold both the phosphorus and sulphur content near the lowerlimit of the workable range of this alloy as hereinbefore described. i 1

These alloys have a melting point of approximately 2250 F., although itmay range from 2000 F. to 2400 F. depending upon the particularpercentages of the component elements of the broad range that is used,especially the element boron which has a marked effect upon the controlof the melting point and when used to reduce the melting point providesan alloy that will flow and deposit easily and soundly on ordinarysteel. The material while described as a hard surface, wearresistlngmetal is also an excellent heat-erosion and corrosion resistant materialbecause of its high nickel-chromium content. There are a number ofhard-facingv materials available but they are usually of such a naturethat when applied to the surface of another metal they react, possiblybecause of having a high melting point, in such a manner that it isdiflicult to produce a finished or ground surface which is free fromsuch defects as blowholes or oxidized areas. Because of the low meltingpoint, provided'in part by the controlled boron content, it readilylends itself to deposition on most steels, and the backing material isnot adversely affected due to the low temperature of application. Forthis reason the alloy should be in the molten condition at approximately2300 F. and this temperature is sufiiciently below the melting point ofordinary steel (2700 F.) to insure the steel tube will still be strongenough to permit the spinning operation. While in the hereinbeforementioned method of lining a cylinder sleeve, or centrifugally castingthe lining alloy in a tube preliminary to removal and subsequentoperations for producing a valve seat ring, it is important that thelining alloy have a melting point not in excess of 2300 F. However; incertain instances the economics of such a method would Justify the useof an alloy steel backing tube which would normally have a highermelting point than the ordinary steel tube previously described, and inthis case the higher melting point of the lining alloy may be safelyutilized. It is also possible to use the alloy in forming a lining byanother method in which the melting point of the alloy is not socritical. In this latter method the molten alloy is poured into aspinning cylinder which is practically at room temperature, and in thiscase the lining material does not adhere to the cylinder, whereas in thefirst method the lining material is bonded to the cylinder.

From a study of the above properties and advantageous features embodiedin this alloy it will be readily apparent that the alloy has decidedmeritorious application for use in valve seat rings and in liningcylinder sleeves for internal combustion engines, where the material issubjected to wear and corrosion both at normal temperatures andrelatively elevated operating temperatures, however, the alloy isequally as well adapted a any use of a similar nature or when placedunder similar conditions, and

while its use and application have been confined 'hereinbefore to avalve seat ring or a cylinder and formal changes may be made in thepercentis believed confined as covered in the following claims.

What I claim is:

1. A cast alloy steel engine part subjected to a normal workingtemperature of several hundred degrees Fahrenheit comprised of carbon.25% to 2.00%, chromium 5% to 15%, silicon .25% to 2.00%, nickel 20% to40%, boron .25% to 3.00%, phosphorus .005% to 2.00%, sulphur .005% to2.00%, and the balance iron, said alloy characterized by a melting pointof 2000 F. to 2400 F.

2. An alloy steel according to claim 1 consisting of carbon .'73%,chromium 8.82%, silicon .87%, nickel 34.27%, boron 1.22%, phosphorus035%, sulphur .86%, and the balance iron.

3. An alloy steel according to claim 1 consisting of carbon .91%,chromium 11.40%, silicon 1.37%, nickel 33.34%, boron 1.78%, phosphorus1.09%, sulphur .02%, and the balance iron.

GEORGE CHARLTON.

